/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.util.scan;

import java.io.IOException;
import java.io.InputStream;

/**
 * Provides an abstraction for use by the various classes that need to scan
 * JARs. The classes provided by the JRE for accessing JARs ({@link java.util.jar.JarFile} and
 * {@link java.util.jar.JarInputStream}) have significantly different performance
 * characteristics depending on the form of the URL used to access the JAR.
 * For file based JAR {@link java.net.URL}s, {@link java.util.jar.JarFile} is faster but for non-file
 * based {@link java.net.URL}s, {@link java.util.jar.JarFile} creates a copy of the JAR in the
 * temporary directory so {@link java.util.jar.JarInputStream} is faster.
 */
public interface Jar {

	/**
	 * Determines if a specific entry exists within the JAR.
	 *
	 * @param name Entry to look for
	 * @return <code>true</code> if the specified entry exists else
	 * <code>false</code>
	 */
	boolean entryExists(String name) throws IOException;

	/**
	 * Obtain an {@link InputStream} for a given entry in a JAR. The caller is
	 * responsible for closing the stream.
	 *
	 * @param name Entry to obtain an {@link InputStream} for
	 * @return An {@link InputStream} for the specified entry or null if
	 * the entry does not exist
	 */
	InputStream getInputStream(String name) throws IOException;

	/**
	 * Close any resources associated with this JAR.
	 */
	void close();

	/**
	 * Moves the internal pointer to the next entry in the JAR.
	 */
	void nextEntry();

	/**
	 * Obtains the name of the current entry.
	 *
	 * @return The entry name
	 */
	String getEntryName();

	/**
	 * Obtains the input stream for the current entry.
	 *
	 * @return The input stream
	 * @throws IOException If the stream cannot be obtained
	 */
	InputStream getEntryInputStream() throws IOException;

	/**
	 * Resets the internal pointer used to track JAR entries to the beginning of
	 * the JAR.
	 *
	 * @throws IOException If the pointer cannot be reset
	 */
	void reset() throws IOException;
}
